Looking for a room for a few days in the month

I am 45, an architect and currently living in St.Gallen together with my partner and our two kids. In January, I will start a new job in Zurich and will therefore stay in Zurich a few days a month.

I'm looking for a room, ideally near a train station (HB, Stadelhofen, Oerlikon) but I am flexibel. I don't need much space. A bed, a small desk, a small cabinet to store some spare clothes would be perfect. In general, I will mostly only be in the apartment to sleep. My budget is around 400CHF (including utilities).
So if you have an extra room but don't want company every day (or week), that would be ideal!

Looking forward to hearing from you!